Effects of aflatoxin b1 on T-cell subsets and mRNA expression of cytokines in the intestine of broilers

Abstract

This study was conducted to investigate the effects of aflatoxin B1 (AFB1) on T-cell subsets and mRNA expression of cytokines in the small intestine of broilers. One hundred and fifty-six one-day-old healthy Cobb broilers were randomly divided into control group (0 mg/kg AFB1) and AFB1 group (0.6 mg/kg AFB1) with three replicates per group and 26 birds per replicate for 21 days, respectively. At 7, 14, and 21 days of age, the duodenum, jejunum and ileum were sampled for analyzing T cell subsets (CD3+, CD3+CD4+ and CD3+CD8+) by flow cytometry as well as IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ and TNF-α mRNA expression by qRT-PCR. The percentages of T-cells in the intra-epithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) of duodenum, jejunum and ileum in the AFB1 group showed a decreased tendency in comparison to the control group. The mRNA expression of cytokines in the three intestinal segments in the AFB1 group presented a general decline compared with the control groups. Our data demonstrated that 0.6 mg/kg AFB1 in the broilers diet could reduce the percentages of T-cell subsets and the expression level of cytokine mRNA in the small intestine, implying that the immune function of the intestinal mucosa might be affected. The reduction of cytokines mRNA expression may be closely associated with the decreased proportions of T cells subsets induced by AFB1.

Figure 1

The quadrantal diagram of the intraepithelial (duodenal, jejunal and ileum) CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺ IELs T-cell percentages in the control and AFB₁ groups at 21 days of age. The numbers in each quadrant indicate the percentage of cells. Panel A: CD3⁺CD4⁺ IELs T-cell in the upper right, and CD3⁺ IELs T-cell in the upper right and upper left; Panel B: CD3⁺CD8⁺ IELs T-cell in the upper right.

Figure 2

Changes of the small intestinal CD3⁺, CD3⁺CD4⁺, and CD3⁺CD8⁺ IELs T-cell percentages and CD4⁺/CD8⁺ ratios at 7, 14 and 21 days of age. Note: Data are presented with the means ± standard deviation (n = 6). * p < 0.05, ** p < 0.01.

Figure 3

The quadrantal diagram of the lamina propria (duodenal, jejunal and ileum) CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺ LPLs T-cell percentages in the control and AFB₁ groups at 21 days of age. The numbers in each quadrant indicate the percentage of cells. Panel A: CD3⁺CD4⁺ LPLs T-cell in the upper right, and CD3⁺ LPLs T-cell in the upper right and upper left; Panel B: CD3⁺CD8⁺ LPLs T-cell in the upper right.

Figure 4

Changes of the small intestinal CD3⁺, CD3⁺CD4⁺, and CD3⁺CD8⁺ LPLs T-cell percentages and CD4⁺/CD8⁺ ratios at 7, 14 and 21 days of age. Note: Data are presented with the means ± standard deviation (n = 6). * p < 0.05, ** p < 0.01.

Figure 5

Levels of the IL-2 (A); IL-4 (B); IL-6 (C) and TNF-α (LITAF) (D) mRNA expression in the small intestine. Data are presented with the means ± standard deviation (n = 6). * p < 0.05, ** p < 0.01.

Figure 6

Levels of the IL-10 (A); IL-17 (B) and IFN-γ (C) mRNA expression in the small intestine. Data are presented with the means ± standard deviation (n = 6). * p < 0.05, ** p < 0.01.